The present invention relates to a feeder sprue system for a casting mold having at least one mold cavity and more particularly a sprue system for a casting mold having first and second casting mold halves.
During the filling of a cast mold, molten metal is fed to the mold cavity via a sprue system. The purpose of the sprue system is to control and guide the flow of the molten metal in order to avoid turbulence thus allowing the entire mold cavity to be filled in the best possible manner. Excess turbulence will result in inclusions in the final cast product. After the mold cavity has been filled with molten metal, it is an intended purpose of the sprue system to provide enough molten metal to top the casting or at the least to assist in topping the casting.
In designing a sprue system particular care must be taken to insure on the one hand that the molten metal is maintained at necessary temperatures when the mold cavity is being filled and on the other hand to avoid the passing of harmful inclusions such as slag, oxides or the like into the mold cavity. Failure to obtain both of the foregoing design parameters results in inferior cast products.
The amount of circulating molten metal is directly proportional to the volume of the total sprue system. There have been many designs in the past for sprue systems. While the sprue systems currently used produce, as a rule, good castings, they suffer from a number of economic disadvantages as pointed out hereinbelow. Firstly, in the sprue system designs presently employed a relatively high proportion of metal remains in the sprue system. In addition, the space requirements for casting molds presently used are relatively large in light of the fact that the casting mold includes not only the mold cavities but also involves pouring systems with slag runners and the like. Finally, after casting, when using present systems, the circulating molten metal must be removed from the sprue system which represents a substantial cost factor.
Accordingly, it is the principal object of the present invention to provide a feeder sprue system for a casting mold which insures high quality castings, short filling times and, is at the same time economical.